Paper updates

I did a bit of polish on the introduction and tried a new introduction to Effects trying to explain the important things in the paper. One thing I also noticed is that the link between Effects and the various EDSLs is maybe not explicit enough so I tried to tie it up a bit more. I don't think I did enough though.

I've also put the Effect declarations (the big code blocks) in figures alongside the protocol descriptions, partly because I think it reads a bit better, and partly to help with layout!

I may get time to do a bit more before the draft proceedings deadline, but don't hold your breath! (I'll be on holiday for a week from this Saturday)